Lee Hsin-Cheng, Li Chung-Tien, Chen How-Foo, Yen Ta-Jen
Opt Lett. 2015 Nov 15;40(22):5152-5. doi: 10.1364/OL.40.005152.
We present an ultrasensitive plasmonic sensing system by introducing a nanostructured X-shaped plasmonic sensor (XPS) and measuring its localized optical properties in phase interrogation. Our tailored XPS exhibits two major resonant modes of a low-order dipole and a high-order quadrupole, between which the quadrupole resonance allows an ultrahigh sensitivity, due to its higher quality factor. Furthermore, we design an in-house common-path phase-interrogation system, in contrast to conventional wavelength-interrogation methods, to achieve greater sensing capability. The experimental measurement shows that the sensing resolution of the XPS reaches 1.15×10(-6) RIU, not only two orders of magnitude greater than the result of the controlled extinction measurement (i.e., 9.90×10(-5) RIU), but also superior than current reported plasmonic sensors.
我们通过引入一种纳米结构的X形等离子体传感器（XPS）并在相位询问中测量其局部光学特性，展示了一种超灵敏的等离子体传感系统。我们定制的XPS呈现出低阶偶极子和高阶四极子的两种主要共振模式，由于四极子共振具有更高的品质因数，因此在这两种模式之间，四极子共振允许实现超高灵敏度。此外，与传统的波长询问方法相比，我们设计了一种内部共光路相位询问系统，以实现更高的传感能力。实验测量表明，XPS的传感分辨率达到1.15×10(-6) RIU，不仅比对照消光测量结果（即9.90×10(-5) RIU）高两个数量级，而且优于目前报道的等离子体传感器。
